Abstract: A developer includes a toner containing toner particles and a carrier containing carrier particles. The toner particles each include a toner mother particle and external additive particles attached to a surface of the toner mother particle. The external additive particles include first silica particles and spacer particles. The first silica particles have a number average primary particle diameter of at least 10 nm and no greater than 30 nm. The spacer particles have a number average primary particle diameter of at least 32 nm and no greater than 145 nm. The spacer particles in the toner particles have a coverage ratio of at least 2.0% by area and no greater than 40.0% by area. The carrier particles each include a carrier mother particle and strontium titanate particles attached to a surface of the carrier mother particle.

Abstract: Toner particles in a developer include first strontium titanate particles attached to the surface of each toner mother particle thereof. The first strontium titanate particles have a content ratio of 0.3 to 0.9 parts by mass to 100.0 parts by mass of the toner mother particles. In the developer, coat layers of carrier mother particles of first carrier particles contain barium titanate particles and a coating resin including silicone resin. The barium titanate particles have a content ratio of 2 to 47 parts by mass to 100 parts by mass of the coating resin. Second strontium titanate particles attached to the surfaces of the carrier mother particles have a diameter of 15 to 85 nm.

Abstract: A developing device includes a developer container, a developer carrier, and first and second stirring/conveying members. The developer container includes a first partition wall partitioning between the two conveying chambers longitudinally, a first communication portion for passing developer from the first to the second conveying chamber, a second communication portion for passing developer from the second to the first conveying chamber, a developer supply port for supplying developer in, a developer discharge portion for discharging excessive developer, a second partition wall arranged, adjacent to the regulating portion, downstream of the second communication portion to partition between the first conveying chamber and the regulating portion, and a shield portion connected to the two partition walls to bridge between them to shield a top part of the second communication portion. A gap is formed between an upper end part of the shield portion and the inner surface of the developer container.

Abstract: An image forming apparatus includes an image carrier, a charging device, an exposure device, a development device, a transferring part, a development bias applying part, an electric current detection part, a density detection part and a bias condition determination part. The bias condition determination part performs a DC voltage determination mode (a DC calibration) determining a reference DC voltage serving as a reference of a DC voltage of a development bias applied to a development roller and a peak-to-peak voltage determination mode (an AC calibration) determining a reference peak-to-peak voltage serving as a reference of a peak-to-peak voltage of an AC voltage of the development bias. When a difference between the reference DC voltages determined the successive DC voltage determination modes exceeds a predetermined threshold value, the bias condition determination part performs the peak-to-peak determination mode.

Abstract: A developing device includes a developer container, a developer carrier, and first and second members for stirring/conveying. The developer container includes a first partition wall between first and second chambers, a communication portion through which those chambers communicate at opposite ends of the first partition wall, a developer supply port, and a developer discharge portion. The first member stirs and conveys developer in the first chamber in a first direction. The second member stirs and conveys developer in the second chamber in a second direction and includes a regulating portion and a discharging blade. The developer container includes a second partition wall between the first chamber and the regulating portion. The gap from the upper end of the second partition wall to the inner surface of the developer container is larger than the gap thereto from the upper ends of a first helical blade and the regulating portion.

Abstract: A developing device includes a developer container, a developer carrier, and first and second stirring/conveying members. The developer container includes a first partition wall partitioning between the two conveying chambers longitudinally, a first communication portion for passing developer from the first to the second conveying chamber, a second communication portion for passing developer from the second to the first conveying chamber, a developer supply port for supplying developer in, a developer discharge portion for discharging excessive developer, a second partition wall arranged, adjacent to the regulating portion, downstream of the second communication portion to partition between the first conveying chamber and the regulating portion, and a shield portion connected to the two partition walls to bridge between them to shield a top part of the second communication portion. A gap is formed between an upper end part of the shield portion and the inner surface of the developer container.

Abstract: A developing device includes a developer container, a developer carrier, and first and second members for stirring/conveying. The developer container includes a first partition wall between first and second chambers, a communication portion through which those chambers communicate at opposite ends of the first partition wall, a developer supply port, and a developer discharge portion. The first member stirs and conveys developer in the first chamber in a first direction. The second member stirs and conveys developer in the second chamber in a second direction and includes a regulating portion and a discharging blade. The developer container includes a second partition wall between the first chamber and the regulating portion. The gap from the upper end of the second partition wall to the inner surface of the developer container is larger than the gap thereto from the upper ends of a first helical blade and the regulating portion.

Abstract: A bias condition determination portion of an image forming device executes each of: a first approximation expression determination operation that respectively acquires the DC component of the development current with at least three peak-to-peak voltages included in a first measurement range and determines a first expression showing a relation between the peak-to-peak voltage and the DC component of the acquired development current, a second approximation expression determination operation that respectively acquires the DC component of the development current with at least three peak-to-peak voltages included in a second measurement range larger than the first measurement range and determines a second approximation expression showing a relation between the peak-to-peak voltage and the DC component of the acquired development current, and a reference voltage determination operation that determines, as a reference peak-to-peak voltage, the peak-to-peak voltage at an intersection where the first approximation exp

Abstract: A bias condition determination portion of an image forming device executes each of: a first approximation expression determination operation that respectively acquires the DC component of the development current with at least three peak-to-peak voltages included in a first measurement range and determines a first expression showing a relation between the peak-to-peak voltage and the DC component of the acquired development current, a second approximation expression determination operation that respectively acquires the DC component of the development current with at least three peak-to-peak voltages included in a second measurement range larger than the first measurement range and determines a second approximation expression showing a relation between the peak-to-peak voltage and the DC component of the acquired development current, and a reference voltage determination operation that determines, as a reference peak-to-peak voltage, the peak-to-peak voltage at an intersection where the first approximation exp

Abstract: Provided is an image forming apparatus capable of suppressing the occurrence of image defects in response to a difference in carrier resistance and obtaining high image quality. A developing unit has a developing roller that carries toner in a two-component developer that includes a toner and a magnetic carrier on the surface thereof, and forms a toner image on the surface of a photosensitive drum. A current detecting unit detects developing current flowing between the developing roller and the photosensitive drum when a developing voltage is applied to the developing roller by a developing power supply. When the developing voltage is applied to the photosensitive drum, a control unit derives a carrier resistance based on the developing current detected by a current detecting unit, and controls an AC amplitude of an AC voltage of the developing voltage based on the carrier resistance.

Abstract: Provided is an image forming apparatus capable of suppressing the occurrence of image defects in response to a difference in carrier resistance and obtaining high image quality. A developing unit has a developing roller that carries the toner in a two-component developer that includes a toner and a magnetic carrier on the surface thereof, and forms a toner image on the surface of a photosensitive drum. A current detecting unit detects developing current flowing between the developing roller and the photosensitive drum when a developing voltage is applied to the developing roller by a developing power supply. When the developing voltage is applied to the photosensitive drum, the control unit derives a carrier resistance based on the developing current detected by a current detecting unit, and controls the AC amplitude of the AC voltage of the development voltage is based on the carrier resistance.

Abstract: An image forming apparatus includes a developing section, storage, a first calculation section, a comparing section, and an executing section. The developing section develops an electrostatic latent image with toner. The storage stores coverage rates. The first calculation section calculates a first coverage rate and a second coverage rate. The comparing section compares the first coverage rate with the second coverage rate. The first coverage rate includes one or more coverage rates stored earlier in the storage than the second coverage rate. The second coverage rate includes coverage rates of a specified number of latest images individually formed on a specified number of sheets. A running-in operation is driving the developing section. The executing section executes the running-in operation.

Abstract: An image forming apparatus includes a developing section, storage, a first calculation section, a comparing section, and an executing section. The developing section contains toner and develops an electrostatic latent image with the toner. The storage stores coverage rates. The first calculation section calculates a first coverage rate and a second coverage rate. The comparing section compares the first coverage rate with the second coverage rate. The executing section executes a running-in operation based on a result of comparison by the comparing section. The first coverage rate includes one or more coverage rates stored earlier in the storage than the second coverage rate. The second coverage rate includes coverage rates of a specified number of latest images individually formed on the specified number of sheets. The running-in operation is driving the developing section.

Abstract: An image forming apparatus includes a developing section, storage, a first calculation section, a comparing section, and an executing section. The developing section develops an electrostatic latent image with toner. The storage stores coverage rates. The first calculation section calculates a first coverage rate and a second coverage rate. The comparing section compares the first coverage rate with the second coverage rate. The first coverage rate includes one or more coverage rates stored earlier in the storage than the second coverage rate. The second coverage rate includes coverage rates of a specified number of latest images individually formed on the specified number of sheets. The running-in operation is driving the developing section. The executing section executes the running-in operation.

Abstract: An image forming apparatus includes a developing section, storage, a first calculation section, a comparing section, and an executing section. The developing section contains toner and develops an electrostatic latent image with the toner. The storage stores coverage rates. The first calculation section calculates a first coverage rate and a second coverage rate. The comparing section compares the first coverage rate with the second coverage rate. The executing section executes a running-in operation based on a result of comparison by the comparing section. The first coverage rate includes one or more coverage rates stored earlier in the storage than the second coverage rate. The second coverage rate includes coverage rates of a specified number of latest images individually formed on the specified number of sheets. The running-in operation is driving the developing section.

Abstract: An image forming apparatus includes a toner containing portion, a first conveying member, an image conveying portion, and an image forming portion. The first conveying member is configured to convey the toner in a conveyance direction within the toner containing portion. The image conveying portion includes a surface layer portion having a first end portion located at an upstream side in the conveyance direction and a second end portion located at a downstream side in the conveyance direction. The first end portion has a larger layer thickness than second end portion. The image conveying portion is configured to convey a toner image formed on a surface of the surface layer portion at a predetermined image forming position, to a transfer position for transfer to a transfer target medium. The image forming portion is configured to form the toner image on the surface layer portion by using the toner being conveyed.

Abstract: An image forming apparatus includes: a photosensitive body including a photosensitive layer having a first end and a second end, the first end having a larger thickness than the second end; a charging portion charges the photosensitive layer; a light irradiation portion applies light to the photosensitive layer; a developing device develops by toner charged with the same polarity as charge polarity of the photosensitive layer; an intermediate transfer medium including a surface layer having a third end and a fourth end, the third end having a larger thickness than the fourth end, the third end being opposed to the second end, the fourth end being opposed to the first end; and a transfer portion transfers a toner image developed on the photosensitive layer, onto the surface layer when a voltage having polarity opposite to the charge polarity is applied to the transfer portion.

Abstract: An image forming apparatus includes a toner containing portion, a first conveying member, an image conveying portion, and an image forming portion. The first conveying member is configured to convey the toner in a conveyance direction within the toner containing portion. The image conveying portion includes a surface layer portion having a first end portion located at an upstream side in the conveyance direction and a second end portion located at a downstream side in the conveyance direction. The first end portion has a larger layer thickness than second end portion. The image conveying portion is configured to convey a toner image formed on a surface of the surface layer portion at a predetermined image forming position, to a transfer position for transfer to a transfer target medium. The image forming portion is configured to form the toner image on the surface layer portion by using the toner being conveyed.

Abstract: An image forming apparatus includes: a photosensitive body including a photosensitive layer having a first end and a second end, the first end having a larger thickness than the second end; a charging portion charges the photosensitive layer; a light irradiation portion applies light to the photosensitive layer; a developing device develops by toner charged with the same polarity as charge polarity of the photosensitive layer; an intermediate transfer medium including a surface layer having a third end and a fourth end, the third end having a larger thickness than the fourth end, the third end being opposed to the second end, the fourth end being opposed to the first end; and a transfer portion transfers a toner image developed on the photosensitive layer, onto the surface layer when a voltage having polarity opposite to the charge polarity is applied to the transfer portion.

Abstract: A developing device includes a housing, a stirring member, a developing unit body, a driving device, a detecting device, and a control device. The housing accommodates developer supplied from a supply means and including toner and carrier. The stirring member rotates in the housing to stir the developer. The developing unit body rotates in the housing to convey the developer toward an image carrying member from the stirring member and attaches the toner to the image carrying member. The driving device rotationally drive at least one of the stirring member and the developing unit body. The detecting device detects the torque of the driving device. The control device performs a recovery process of controlling the supply means to supply at least one of the carrier and the developer to an interior of the housing when a detection result of the detecting device has a value lower than a threshold value.